Cisapride Induces Clustered Spikes and Irregular Spiking of the Small Intestine of the Rat

Abstract

The aim of the present study was to investigate the effect of cisapride on the myoelectric activity of the small intestine in the rat. Intestinal myoelectric activity of fasted conscious rats was monitored by three bipolar electrodes chronically implanted at 5, 15 and 25 cm distal to the pylorus and connected to an EEG amplifier. In the basal state, regularly occurring migrating myoelectric complexes (MMCs) and clustered spikes were registered. Cisapride at doses of 0.5- 4.0 mg⁻¹ i.v. did not affect the MMCs, but at 8 mg kg⁻¹ i.v. the regular MMCs were replaced by irregular spiking activity (p<0.05). Concomitantly cisapride increased the occurrence of clustered spikes and abbreviated the interval between them in a dose-dependent manner (p<0.05), without affecting their duration. Hexamethonium at a dose of 10 mg kg⁻¹ i.v. abolished the MMCs as well as the stimulatory effect of ciapride (4 mg kg⁻¹). Atropine at a dose of 1 mg kg⁻¹ i.v. did not affect the MMCs but blocked the stimulatory effect of cisapride (4 mg kg⁻¹). It is concluded that cisapride induces clustered spikes and irregular spiking. These effects require intact cholinergic pathways, involving both muscarinic and nicotinic receptor mechanisms.

Key Words:

• Cisapride
• MMC
• myoelectric activity
• small intestine